The present invention relates to a quick coupling with a connecting, respectively a releasing, capability in the presence of a pressurized hydraulic fluid.
Quick couplings or fittings, in particular of a so-called “push-pull” type for coupling resilient pipes conveying a pressurized fluid are already commercially available.
Said fittings comprise a tubular element and a rod like-element, which can be coupled to one another under a pushing force, or can be disengaged from one another by applying on the fitting elements a pulling force.
In a particular advantageous manner, the above mentioned connecting and releasing operations can be also carried out as pressurized fluid are present in the pipes and in the quick coupling constructional elements.
To perform the mentioned connecting and releasing operations as a high pressure is present in said pipes or hydraulic devices, the coupling tubular element comprises in inner bleeding means allowing to drain a comparatively high fluid amount, to reduce or release the pressure in said quick tubular coupling, thereby facilitating the connecting and releasing operations.
In prior quick couplings, the hydraulic fluid draining or bleeding is performed by complex bleeding valves arranged in the tubular element, which bleeding valves, in particular, comprise sealing means, valve seats and urging springs urging the valve stems of rods toward a closure position thereof.
Thus, in assembling the quick coupling elements, the bleeding valves are urged by a pushing force, to be disengaged from their seats, for allowing the pressurized hydraulic fluid to partially flow.
However, as it should be apparent, the provision of a bleeding valve would allow a coupling or releasing operation to occur also when the quick coupling is subjected to hydraulic pressure; accordingly, in this case, the quick coupling would have a very complex construction including a plurality of mechanical elements to form said bleeding valve to be installed in the coupling body, which bleeding valve, moreover, will occupy a comparatively large space and, consequently, also the quick coupling will disadvantageously have a large size.